Closed Loop Fluid Resuscitation Control Via Blood Volume Estimation

Abstract

This paper presents a closedloop control of fluid resuscitation to overcome hypovolemia based on modelbased estimation of relative changes in blood volume (BV). In this approach, the control system consists of a modelbased relative BV (RBV) estimator and a feedback controller. The former predicts relative changes in the BV response to augmented fluid by analyzing an arterial blood pressure (BP) waveform and the electrocardiogram (ECG). Then, the latter determines the amount of fluid to be augmented by comparing target versus predicted relative changes in BV. In this way, unlike many previous methods for fluid resuscitation based on controlled variable(s) nonlinearly correlated with the changes in BV, fluid resuscitation can be guided by a controlled variable linearly correlated with the changes in BV. This paper reports initial design of the closedloop fluid resuscitation system and its in silico evaluation in a wide range of hypovolemic scenarios. The results suggest that closedloop fluid resuscitation guided by a controlled variable linearly correlated with the changes in BV can be effective in overcoming hypovolemia: across 100 randomly produced hypovolemia cases, it resulted in the BV regulation error of 7.98 آ±â€‰171.6 ml, amounting to 0.18 آ±â€‰3.04% of the underlying BV. When guided by pulse pressure (PP), a classical controlled variable nonlinearly correlated with the changes in BV; the same closedloop fluid resuscitation system resulted in persistent underresuscitation with the BV regulation error of −779.1 آ±â€‰147.4 ml, amounting to −13.9 آ±â€‰2.65% of the underlying BV.